1. Field of the Invention
The present invention relates to an endoscope that changes a tilting direction and a tilting angle of a manipulator provided at an operation portion to move a pulling member, thereby performing an operation to bend a bending portion provided in an insertion portion.
2. Description of the Related Art
In recent years, in a medical field and an industrial field, endoscopes including an elongated insertion portion have been used. With the endoscopes in the medical field, the insertion portion is inserted into a body from, e.g., an oral cavity or an anus to perform, e.g., observation. On the other hand, with the endoscopes in the industrial field, the insertion portion is inserted into, e.g., a piping of a boiler or an inner portion of an engine to perform observation.
In such endoscopes, a bending portion that bends, e.g., upward, downward, rightward and leftward is provided on the distal end side of the insertion portion. The endoscopes provided with the bending portion enable an observation optical system provided in a distal end portion to be directed to a desired direction by performing an operation to bend the bending portion.
In an operation portion provided on the proximal end side of the insertion portion including the bending portion, a bending knob for performing an operation to bend the bending portion, for example, upward/downward or leftward/rightward is pivotably provided. Respective one ends of bending wires corresponding to the respective bending directions are joined to predetermined positions in the bending portion and the respective other ends of the bending wires are joined to the bending knob.
With an endoscope with such configuration, an operator arbitrarily rotates the bending knob clockwise or counterclockwise by the fingers of the hand grasping the operation portion, to pull or loosen the joined bending wires, whereby the bending portion is bent. In recent years, there have been proposed endoscopes provided with drive means inside the operation portion of the respective endoscope, in which bending wires are pulled or loosened by operating a manipulator, which is a bending mechanism, by the fingers, enabling the bending portion to be bent in a desired direction.
In the endoscope according to Japanese Patent Application Laid-Open Publication No. 2003-325437, respective bending wires are wound and arranged in advance on a pulley that rotates by means of a motor, which is drive means, in a predetermined loosened state. When an operator performs an operation to bend the bending portion, the operator performs an operation to tilt an operation instruction lever (corresponding to a manipulator in the present description), which is a manipulator. Then, a bending wire corresponding to the tilting direction of the operation instruction lever is pulled and brought into contact with the pulley. Then, a resistive force between the bending wire and the pulley increases, whereby the wire is moved in a rotation direction of the pulley and the bending portion is bent in a desired direction.
In other words, in the endoscope described above, a bending wire pulling force amount for moving the bending wire can be obtained by the rotating pulley to perform an operation to bend the bending portion. In other words, the following equation can be provided:Bending wire pulling force amount=Operation instruction lever tilting operation force amount+Assist force amount.
With an endoscope with such configuration, an operation force amount for performing an operation to tilt an operation instruction lever can be reduced to reduce the burden of an operator.
Here, “assist force amount” refers to auxiliary power for moving a bending wire, which can be obtained from a rotating pulley.
Also, Japanese Patent Application Laid-Open Publication No. 2009-5836 indicates an endoscope including a pulling member operation apparatus according to above-mentioned Japanese Patent Application Laid-Open Publication No. 2003-325437, the endoscope including a bending mechanism enabling a bending portion to be bent efficiently relative to an amount of pulling a pulling member by an operation portion, without an increase in size of an operation portion.